typescript-method-decorator.ts

typescript-method-decorator.ts

// Edit on https://gist.github.com/jotafeldmann/c3129225ba5d0c26b5fb32273752e8fc
// Test on https://replit.com/@jotafeldmann/typescript-method-decorator#index.ts
// "experimentalDecorators": true

function log(target: any, propertyName: string, descriptor: PropertyDescriptor) {
    const originalMethod = descriptor.value;

    descriptor.value = function (...args: any[]) {
        const result = originalMethod.apply(this, args);
        console.log(`${propertyName}(${args}) = ${result}`);
        return result;
    };

    return descriptor;
}

// Usage:

class AnyClass {
  @log
  private privateMethod(arg: string): boolean {
    return arg === "1";
  }

  @log
  public publicMethod(arg: string): boolean {
    return this.privateMethod(arg);
  }
}

const anyClass = new AnyClass();

anyClass.publicMethod("2");